atl1: fix oops when changing tx/rx ring params

atl1: fix oops when changing tx/rx ring params

Commit 0e2954e1884d1d5a9e9540576a5f20b594a573b5 zeroes out the statistics
message block (SMB) and coalescing message block (CMB) when adapter ring
resources are freed.  This is desirable behavior, but, as a side effect,
the commit leads to an oops when atl1_set_ringparam() attempts to alter
the number of rx or tx elements in the ring buffer (by using ethtool
-G, for example).  We don't want SMB or CMB to change during this
operation.

Modify atl1_set_ringparam() to preserve SMB and CMB when changing ring
parameters.

Cc: stable@kernel.org
Signed-off-by: Jay Cliburn <jcliburn@gmail.com>
Reported-by: Tõnu Raitviir <jussuf@linux.ee>
Signed-off-by: David S. Miller <davem@davemloft.net>